There’s something wrong about the displays laid out on Al’s pastry counter — no symmetry. One covered platter holds eight pinwheels in a ring about a central one, but the other platter’s central pinwheel has only a five-pinwheel ring around it. I yell over to him. “What’s with the pastries, Al? You usually balance things up.”
“Ya noticed, hey, Sy? It’s a tribute to the Juno spacecraft. She went into orbit around Jupiter on the 5th of July 2016 so I’m celebrating her anniversary.”
“Well, that’s nice, but what do pinwheels have to do with the spacecraft?”
“Haven’t you seen the polar pictures she sent back? Got a new poster behind the cash register. Ain’t they gorgeous?”
“They’re certainly eye-catching, but I thought Jupiter’s all baby-blue and salmon-colored.”
Astronomer Cathleen’s behind me in line. “It is, Sy, but only in photographs using visible sunlight. These are infrared images, right, Al?”
“Yeah, from … lemme look at the caption … Juno‘s JIRAM instrument.”
“Right, the infrared mapper. It sees heat-generated light that comes from inside Jupiter. It’s the same principle as using blackbody radiation to take a star’s temperature, but here we’re looking at a planet. Jupiter’s way colder than a star so the wavelengths are longer, but on the other hand it’s close-up so we don’t have to reckon with relativistic wavelength stretching. At any rate, infrared wavelengths are too long for our eyes to see but they penetrate clouds of particulate matter like interstellar dust or the frigid clouds of Jupiter.”
“So this red hell isn’t what the poles actually look like?”
“No, Al, the visible light colors are in the tops of clouds and they’re all blues and white. These infrared images show us temperature variation within the clouds. Come to think of it, that Hell’s frozen over — if I recall correctly, the temperature range in those clouds runs from about –10°C to –80°C. In Fahrenheit that’d be from near zero to crazy cold.”
“Those aren’t just photographs in Al’s poster?”
“Oh, no, Sy, there’s a lot of computer processing in between Juno‘s wavelength numbers and what the public sees. The first step is to recode all the infrared wavelengths to visible colors. In that north pole image I’d say that they coded red-to-black as warm down to white as cool. The south pole image looks like warmest is yellow-to-white, coolest is red.”
“How’d you figure that?”
“The programs fake the apparent heights. The warmest areas are where we can see most deeply into the atmosphere, which would be at the center or edge of a vortex. The cooler areas would be upper-level material. The techs use that logic to generate the perspective projection that we interpret as a 3-D view.”
Vinnie’s behind us in line and getting impatient. “I suppose there’s Science in those pretty pictures?”
“Tons of it, and a few mysteries. JIRAM by itself is telling the researchers a lot about where and how much water and other small molecules reside in Jupiter’s atmosphere. But Juno has eight other sensors. Scientists expect to harvest important information from each of them. Correlations between the data streams will give us exponentially more.”
He’s still antsy. “Such as?”
“Like how Jupiter’s off-axis magnetic field is related to its lumpy gravitational field. When we figure that out we’ll know a lot more about how Jupiter works, and that’ll help us understand Saturn and gas-giant exoplanets.”
Al breaks in. “What about the mysteries, Cathleen?”
“Those storms, for instance. They look like Earth-style hurricanes, driven by upwelling warm air. They even go in the right direction. But why are they crammed together so and how can they stay stable like that? Adjacent gears have to rotate in opposite directions, but these guys all go in the same direction. I can’t imagine what the winds between them must be like.”
“And how come there’s eight in the north pole ring but only five at the other pole?”
“Who knows, Vinnie? The only guess I have is that Jupiter’s so big that one end doesn’t know what the other end’s doing.”
“Someone’s gonna have to do better than that.”
“Give ’em time.”
~~ Rich Olcott
“So you’re telling me, Cathleen, that you can tell how hot a star is by 
Cathleen turns to her laptop and starts tapping keys. “Let’s do an example. Suppose we’re looking at a star’s broadband spectrogram. The blackbody curve peaks at 720 picometers. There’s an absorption doublet with just the right relative intensity profile in the near infra-red at 1,060,190 and 1,061,265 picometers. They’re 1,075 picometers apart. In the lab, the sodium doublet’s split by 597 picometers. If the star’s absorption peaks are indeed the sodium doublet then the spectrum has been stretched by a factor of 1075/597=1.80. Working backward, in the star’s frame its blackbody peak must be at 720/1.80=400 picometers, which corresponds to a temperature of about 6,500 K.”
“You’re right, Sy. It’s not a particularly pretty picture, but it shows that nice strong sodium doublet in the yellow and the broad iron and hydrogen lines down in the green and blue. I’ll admit it, Vinnie, this is a faked image I made to show my students what the solar atmosphere would look like if you could turn off the photosphere’s continuous blast of light. The point is that the atoms emit exactly the same sets of colors that they absorb.”
“Whoa, Sy. Do you read the final chapter of a mystery story before you begin the book?”
“It is, Sy, and that’s one of the reasons why Hubble’s original number was so far off. He only looked at about 50 close-by galaxies, some of which are moving toward us and some away. You only get a view of the general movement when you look at large numbers of galaxies at long distances. It’s like looking through a window at a snowfall. If you concentrate on individual flakes you often see one flying upward, even though the fall as a whole is downward. Andromeda’s 250,000 mph march towards us is against the general expansion.”
“Infinite?”
The thing about Al’s coffee shop is that there’s generally a good discussion going on, usually about current doings in physics or astronomy. This time it’s in the physicist’s corner but they’re not writing equations on the whiteboard Al put up over there to save on paper napkins. I step over there and grab an empty chair.
Hard Science Ain't Hard 
